Prevention of mud cutting in earth boring drills



Nov. 6, 1956 PREVENTION OF MUD CUTTING IN EARTH BORING DRILL-S Original Filed July 15, 1950 Fly. 4

ERW/N A. MoRLAN Haw/2y 8' W0 VENT 0R3 BYQ M ATTORNEY E. A. MORLAN ETAL 2,769,616 r -PREVEN-ION OFMUD-CUTTING IN EARTH BORING DRILLS 'ErwinAfMoilan and Henry B. Woods, Houston, Tex.,-as- :signors to Hughes Tool Company, Houston, Ten, 7 a :corporation of Delaware 'Continnafion of application Serial No.

174,024, July 15, This application February 9, 1953, SerialNo.

' 6 Claims. (Cl. 255-4508) fIhisinvention-relates to well drills of the rolling cutter :type whereintoothed rolling cutters roll upon and disintegratethe bottom of a well bore in accordance with the rotary method of drilling.

This application is a continuation of our prior applica- :tion1Serial No. 174,024, filed July 15, 1950, now abandoned.

Inthe drilling of wells, such'as .oil and gas wells, by .the rotary method of drilling, abit'head is provided with a;plurality:of rolling .cutters mounted upon shafts, or :spindles, at'the lower end of the head. Usually antifrictionbearings are-interposed between each cutter and -itsishaft proximate the shoulder on the head at the end of the --rspindle,'the end of the cutter being in opposed :spaced relation with the shoulder. .In the use of drills of -this: type difiiculty has'beenexperienced in aphenomenon which has becomelrnown as mud cutting. When'this condition develops it seems that particles from the flush- .ingfinid and/orparticlesdisintegrated from the bottom *of thewell bore collect upon the end of the rolling cutter, Iinthespace between the cutterand the shoulder revolve with the cutter and act as an abrasive to cut away the .metal of the shoulder at the base .of the spindle. .Even though the particles do not form a solidmass, butiare constantly'disintegrating and building up, they function to cut away the shoulder and the spindle at the-juncture thebitlegwhereby cutting action of the bit'is impaired and eventually the bearings are released, cuttting action is terminated and the cutter may, especially on the acone type of 'well drill, be lost in the hole.

The primary object of our invention is to prevent mud cutting inthe rolling cutter type of well drills.

:Another object is to provide a slug or patch of wear resistantmaterial within the area subject to mud cptting Ito-disintegrate the accumulating abrasive material that would otherwise effect mud cutting, and in this manner, ito .prevent .mud cutting throughout the entire surface where such action usually occurs.

Another and 'more specific object is to form a subistantiallyiradially etxending slot or groove in thezshoulder :atftherbasexof the spindle of a rolling cutter type of well ;drill;and1to thereafter secure a wear resistant material within-such. groove, such material either filling or partially filling the. groove.

The invention also comprehends that the material filling or partially filling the. groove shall continue over and upon the outer surface of the bit leg at the end of the groove thereby preventing undercutting of the wear resistant material atthe end of the groove.

The foregoing objects together with other objects and advantages ofthe invention will be more fully apparent from thefollowing-description considered in connection -with the accompanying drawings in which:

FigJl is a side view, in broken elevation and partly "in section, of acne type well drill embodying the invention;

Fig. 2 is a sectional view taken on line 22 in Fig. 1;

'rection of rotation of the cutter.

Patented Nov. 6, i956 Fig. 3 is an enlarged detail, partly in section, takencn fline 3-3 of Fig. *2 and showing one form of wear're sistant pad use'd in accordancewith the invention;

Fig. 4 is a view similar to Fig. 2 but showing a difierent orientation of the wear resistantpads;

Fig. 5 is a detail showing the manner of using'a single compact or slug of wear resistant material to prevent mud cutting in accordance with the invention;

7 Fig. 6 is a view similar to'Fi'g. 2 but showing another manner of practicing the invention.

'While the invention isillustrated in the drawings "as embodied in'the cone type of well drill it'is intended that such showing shall be considered as merely illustrative since the invention is also applicable'in other types of well 'drill utilizing rolling cutters.

In the drawings there is shown a cone'type "of'well drill 1 of conventional construction and comprising 'a head 2 with an upwardly'taperedand threaded shank 3 for-engagement'with a drill collar ortool joint. At the lower or forward end of the drill are downwardly extending legs 4, one of which is shown in section in Fig. 1.

"The-destructiveefiects ofmud cutting tobe eliminated in accordance with the invention are produced by an accumulation of abrasive material on the base 6 0f the cutterS'mounted on the spindle 7, 'antifriction bearings 8 and 9 being'interpose d betwen thespindle 7 andthe inner bearing surface ofthe cutterite assume axial'a'n'd radial loads upon the cutter. This abrasive material,

traveling with the cutter 5 during its rotation'on the shaft *7,-'efiects-scoring or cutting away'of the shoulder 10"at the base of the spindle even'thoughthesesurfaces'nominally are held in spaced relation by the bearing structure just described and as is clearly'shown in Fig. 1. This'is 'a progressive action which'removes' material fromthe shoulder as indicated by successive dotted lines 11. The

e ftectiveness oft'ne-well drill'is impaired at'the outset but eventually the destruction is'such'that the bearings are released and cutting action of'the drill is'terminated.

We'have found that mud cutting,as above explained can be eliminated by the proper'application of awear resistant material upon a portion'only of the shoulder '10 as'shown in-Figs. 2and 3. As shown in these'fig ures a 'pair'ofrecesses or; grooves 15 and 16 are forme din the shoulder 10. These recesses-or groovesextend 'substantially radially of the shoulder '10 and are locatedangularly a short distance from the lowermost'pointon the cutter in the direction indicated 'by'the arrow 17, the'di- A pad of wearresistant material 18 is deposited in each of the'recesses or grooves 15 and 16, such materialhaving its'outer surface substantially flush with the adjacent surface of 'theshoulder '10. Where therecesses'lS and 16 intersect theouter'surface of the leg 4 we preferably extendthe material of 'the pad 18 to cover a small portion of such outer surface as shown at,19 inFig. 3 to prevent undercutting of the Wear resistant material inthegroove 15 M16 at that point.

*Inthis figureaportionof this-extension area is cut away to show the relative position of the-extension and the pad 18.

By-ntilizing a pad orpads of wear resistant material,

An alternate arrangement for'the wear resistant'pads is shown in Fig.4 wherein'the pads areshown-in-angularlyspaced'relation'at 2D and 21.

The pad '18 is preferably deposited in the groove is -or ilfi by a'torchapplication-such-asis used for building'up surfaces with a wear resistant material, such as tungsten carbide particles with a matrix metal of mild steel, other metal or alloy.

Still another embodiment or form of the invention is shownin..Fig..5..wherein a recess 22-is providedin' the fslio'ulder 10.. and a preformed pad 23 is secured in such recess in any suitable manner such as brazing or the like. A pad. suitable for this purpose may comprise a body of sintered carbide although'it is to'be understood that mention of a particular material is illustrative only as any suitable material may be used without departing from the spirit of the invention.

In stillanother form of theinvention, as illustrated inIFig. 6 a recess 25 is provided-in the shoulder 10 at the base of the spindle 7. This recess extends outwardlyand forwardly relative to the direction of rotation of the cutter as indicated by. the arrow- 17. A quantityof wear resistant metal 26 is deposited in the recess 25 in the manner already described in connection with grooves 15 and 16 inthe embodiment shown in Figs. 1, 2'and 3. This wardlywhereby destructive effects upon the bit head are avoided.

.- While the width and depth of the grooves 15, 16 and ,25 may vary, it has beenfound that a width of five- .sixteenths of an inch and a depth of one-sixteenth inch are satisfactory. It has also been found that an extension '19 of the hard facing'metal of one-half inch on the periphery of the leg beyond the outer end of the groove will adequately protect: the pad of wear resistant material from undercutting at that point.

Construction and use of the iIlVGIltlOIl are believed apparent from the foregoing description. By way of reiteration and supplementation it will be assumed that a quantity of wear resistant material is secured upon the shoulder 10 in a manner heretofore described. When the I bit 1 is innormal operation, abrasive material collecting upon'and moving with the base 6 of the cutter 5 moves in the direction of thearrow 17 and contacts the wear re- .sistant material secured upon the shoulder 10. Such contact effects progressive disintegration of the mass of abrasive material-whereby mud cutting of the shoulder 10 and the adjacent spindle are avoided. While there is a tendency for the substantially radially extending pads of Figs. 1 to 5 to cause the abrasive mud particles to slough off at the periphery of the shoulder 10 as the cutter'rotates in the direction of the arrow 17, this action is accentuated in the embodiment of Fig. 6 which shows an important form of the invention.

' Broadly the invention comprehends a drill bit structure -which includes .areas of wear resistant material so located and. oriented as to effectively disintegrate abrasive material which tends to effect mud cutting.

' The invention claimed is:

1. In a well drill, a head, a downwardly extending leg thereon, a shaft integral with andextending inwardly from saidleg, there being a shoulder at the juncture of said leg and shaft, a cutter rotatively mounted on said shaft and having a portion in confronting spaced relation with said shoulder, a radially extending recess in said shoulder, and wear resistant material secured in and filling said recess, the surface of said wear resistant material being in spaced relation withthe'confronting portion of. said' cutter so that saidwear resistant jmaterial efiects progressive disintegration of abrasive material that builds upon the cutter, travels wih the cutter and tends V .to produce mud cuttingupon said shoulder.

2. In a well drill, a head, a downwardly extending leg thereon, a shaft integral with and extending inwardly from said leg, there being a shoulder at the juncture of tion with said shoulder, .a radially extending recess in 1 i said shoulder, and wear resistant material secured in and filling said recess, said wear resistant material including a continuation covering and bonded to an area on the periphery of the bit leg at the .outer end of the recess. 3. In a well drill, a head, a downwardly extending leg thereon, a shaft integral with and extending inwardly from said leg, there being a shoulder at the juncture of said leg and shaft, a :cutter, rotatively mounted on'said shaft and having a portion in confronting spaced relation with said shoulder, a pair of recessesin said shoulder and extending substantially radially thereof, and wear resistant material secured in and filling said recesses, the surface of said wear resistant material being in spaced relation with the confronting portion of said cutter so that said wear resistant material" effects progressive'disintegration of abrasive material that builds up on the cutter, travels with the cutter "and tendsto produce mud cutting upon said shoulderi j 4. In a'well drill, ahead, a1 downwardly extending leg thereon, a shaft integral with and extending inwardly from said leg, there being a shoulder at the juncture of said leg and shaft, a cutter rotatively mounted on said shaft and havinga portion in confronting spaced'r'elation with said shoulder, a pairof recesses said shoulder and extending substantially radiallythereof, and wear resistant material secured in, filling said recesses, and extending outwardly andbonded to an area on'the periphery of the bit leg at the outer ends ofthe-rece'sses.

5.- In a well drill, a head, a downwardlyextendin'gleg V thereon, a shaft integral with and extending inwardly fromsaid leg, there being a shoulder at the juncture of said leg and shaft, a. cutter rotatively mounted on said shaft and having a portion in confronting spaced relation 'withsaid. shoulder, a recess in-said shoulder extending outwardly from the shaft,-forwardly in the direction of rotation of thecutteron the shaft'and terminating 'at 'it's outer end in the peripheral surface of lthe leg; and-a "quantityof wear resistant material bonded to theside walls and bottom of the recess. so that said wear resistantsaid leg and shaft, alcutter. rotatively mounted onsaid 'shaftland having a'portion injconfrontingi spaeedrela- "tion with said shoulder; a recess in said shoulder extend ing outwardly from the shaft, forwardly in.the directlon of rotation'of the cutter on the shaft and terminating at is outer end-in the peripheral surface oflthe leg,.and a quantity of wear resistant material b'onded to the: side -wallsand bottom "of the recess so that said wear resistant material eifects progressive;disintegration of'abrasive' material that builds 'up. on the cutt er. and tends Ioelfect mud cutting of th'e'shoulder, 'saidfwear resistant material extending beyond the 'outer'endiof said" recess'andxbemg bonded to the periphery ofthe bit leg proximate the outer "end of therecess. U t V V w References cirea inthefileof this patent f 7 UNITED STATES PATENTS; 7 2

1,306,371 Culmore June .10, 1919' 1,641,261' Fletcher; iSept; 6, 1927 1,835,701 "Edmunds" .Dec 8,1931 1,855,330 "Zublin-zr; A an-26,1932 1,856,627 Fletcher: May 3 1 932, 1,973,657 Pickin w x 7 Sept 11,1934. 2,057,209 1 Schlumpf -Oct..13, .1936 Nov. 4,1941

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